Effects of rumen-bypass protein supplement on growth performance, hepatic mitochondrial protein complexes, and hepatic immune gene expression of beef steers with divergent residual feed intake.

We investigated the impact of a rumen-bypass protein (RBP) supplement on growth performance, plasma and urinary N (UN) concentration, hepatic mitochondrial protein complexes, and hepatic mRNA expression of immune genes of beef steers with negative or positive residual feed intake (RFI) phenotype. Forty crossbred beef steers with an average body weight (BW) of 492 ± 36 kg were subjected to a generalized randomized block design over a 42-day experimental period. This study followed a 2 × 2 factorial arrangement of treatments. The factors evaluated were: 1) RFI classification (low-RFI (-2.12 kg/d) vs. high-RFI (2.02 kg/d), and 2) rumen-bypass protein supplement: RBP supplement (RBP; 227 g/steer/d) vs. control diet (CON; 0 g/d), resulting in four distinct treatments: LRFI-CON (n = 10), LRFI-RBP (n = 10), HRFI-CON (n = 10), and HRFI-RBP (n = 10). The RBP supplement (84% crude protein) is a mixture of hydrolyzed feather meal, porcine blood meal, and DL-methionine hydroxy analogue. The beef steers were stratified by BW, randomly assigned to treatments, and housed in four pens (1 treatment/pen) equipped with two GrowSafe feed bunks each to measure individual dry mater intake (DMI). Body weight was measured every 7 d. Liver tissue samples were collected on d 42 from all the beef steers. These samples were used for mRNA expression analysis of 16 immune-related genes and for evaluating the mitochondrial protein complexes I - V. No significant effects due to RBP supplementation or RFI × RBP interactions (P > 0.05) were observed for average daily gain (ADG) and DMI. However, compared to high-RFI steers, low-RFI steers showed a trend towards reduced DMI (12.9 vs. 13.6 kg/d; P = 0.07) but ADG was similar for the two RFI groups. Regardless of RFI status, supplemental RBP increased blood urea nitrogen (BUN) (P = 0.01), with a lower BUN concentration in low-RFI steers compared to high-RFI ones. A tendency for interaction (P = 0.07) between RFI and RBP was detected for the UN concentrations; feeding the dietary RBP increased the UN concentration in high-RFI beef steers (209 vs. 124 mM), whereas the concentration was lower than that of the CON group for low-RFI beef steers (86 vs. 131 mM). Interactions of RBP and RFI were observed (P ≤ 0.05) for mitochondrial activities of complexes IV, V, and mRNA expressions of some immune genes such as TLR2, TLR3, and IL23A. In conclusion, while RBP supplementation did not alter growth performance, its observed effects on hepatic immune gene expression, mitochondrial protein complexes, BUN, and UN depended on the beef steers' RFI phenotype. Therefore, the RFI status of beef steers should be considered in future studies evaluating the effects of dietary protein supplements.

Association of litter size with the ruminal microbiome structure and metabolomic profile in goats.

The Yunshang black goat is a renowned mutton specialist breed mainly originating from China that has excellent breeding ability with varying litter sizes. Litter size is an important factor in the economics of goat farming. However, ruminal microbiome structure might be directly or indirectly regulated by pregnancy-associated factors, including litter sizes. Therefore, the current experiment aimed to evaluate the association of different litter sizes (low versus high) with ruminal microbiome structure by 16S rRNA gene sequencing and metabolomic profiling of Yunshang black does. A total of twenty does of the Yunshang Black breed, approximately aged between 3 and 4 years, were grouped (n = 10 goats/group) into low (D-l) and high (D-h) litter groups according to their litter size (the lower group has ≤ 2 kids/litter and the high group has ≧ 3 kids/litter, respectively). All goats were sacrificed, and collected ruminal fluid samples were subjected to 16S rRNA sequencing and LC-MS/MC Analysis for ruminal microbiome and metabolomic profiling respectively. According to PCoA analysis, the ruminal microbiota was not significantly changed by the litter sizes among the groups. The Firmicutes and Bacteroidetes were the most dominant phyla, with an abundance of 55.34% and 39.62%, respectively. However, Ruminococcaceae_UCG-009, Sediminispirochaeta, and Paraprevotella were significantly increased in the D-h group, whereas Ruminococcaceae_UCG-010 and Howardella were found to be significantly decreased in the D-l group. The metabolic profiling analysis revealed that litter size impacts metabolites as 29 and 50 metabolites in positive and negative ionic modes respectively had significant differences in their regulation. From them, 16 and 24 metabolites of the D-h group were significantly down-regulated in the positive ionic mode, while 26 metabolites were up-regulated in the negative ionic mode for the same group. The most vibrant identified metabolites, including methyl linoleate, acetylursolic acid, O-desmethyl venlafaxine glucuronide, melanostatin, and arginyl-hydroxyproline, are involved in multiple biochemical processes relevant to rumen roles. The identified differential metabolites were significantly enriched in 12 different pathways including protein digestion and absorption, glycerophospholipid metabolism, regulation of lipolysis in adipocytes, and the mTOR signaling pathway. Spearman's correlation coefficient analysis indicated that metabolites and microbial communities were tightly correlated and had significant differences between the D-l and D-h groups. Based on the results, the present study provides novel insights into the regulation mechanisms of the rumen microbiota and metabolomic profiles leading to different fertility in goats, which can give breeders some enlightenments to further improve the fertility of Yunshang Black goats.

In vitro fermentation end-products and rumen microbiome as influenced by microencapsulated phytonutrient pellets (LEDRAGON) supplementation.

The objective of this study was to investigate the effect of microencapsulated bioactive compounds from lemongrass mixed dragon fruit peel pellet (MiEn-LEDRAGON) supplementation on fermentation characteristics, nutrient degradability, methane production, and the microbial diversity using in vitro gas production technique. The study was carried out using a completely randomized design (CRD) with five levels of MiEn-LEDRAGON supplementation at 0, 1, 2, 3, and 4% of the total dry matter (DM) substrate. Supplementation of MiEn-LEDRAGON in the diet at levels of 3 or 4% DM resulted in increased (p < 0.05) cumulative gas production at 96 hours (h) of incubation time, reaching up to 84.842 ml/ 0.5 g DM. Furthermore, supplementation with 3% MiEn-LEDRAGON resulted in higher in vitro nutrient degradability and ammonia-nitrogen concentration at 24 h of the incubation time when compared to the control group (without supplementation) by 5.401% and 11.268%, respectively (p < 0.05). Additionally, supplementation with MiEn-LEDRAGON in the diet led to an increase in the population of Fibrobacter succinogenes at 24 h and Butyrivibrio fibrisolvens at 12 h, while decreasing the population of Ruminococcus albus, Ruminococcus flavefaciens, and Methanobacteriales (p < 0.05). Moreover, supplementation of MiEn-LEDRAGON in the diet at levels of 2 to 4% DM resulted in a higher total volatile fatty acids (VFA) at 24 h, reaching up to 73.021 mmol/L (p < 0.05). Additionally, there was an increased proportion of propionic acid (C3) and butyric acid (C4) at 12 h (p < 0.05). Simultaneously, there was a decrease in the proportion of acetic acid (C2) and the ratio of acetic acid to propionic acid (C2:C3), along with a reduction of methane (CH4) production by 11.694% when comparing to the 0% and 3% MiEn-LEDRAGON supplementation (p < 0.05). In conclusion, this study suggests that supplementing MiEn-LEDRAGON at 3% of total DM substrate could be used as a feed additive rich in phytonutrients for ruminants.

TLR5 ligand induces the gene expression of antimicrobial peptides and CXCL8 through IL-1ß gene expression in cultured rumen epithelial cells.

High grain feeding or weaning, which could compromise the rumen epithelium by increasing ruminal short-chain fatty acid (SCFA) concentrations with pH reduction, is associated with high levels of ruminal toll-like receptor 5 (TLR5). This study aimed to determine the role of TLR5 in the rumen epithelium. Immunohistochemistry revealed that TLR5 was localized in cells on the basal side (i.e., basal and spinous layers) rather than in the granular layer in the rumen epithelium, where tight junctions are most potent, in pre- and post-weaning calves (n = 9). Primary bovine rumen epithelial cells (BRECs) obtained from Holstein cows (n = 3) were cultured to investigate the factors that upregulate TLR5; however, SCFA, low pH (pH 5.6), BHBA, L-lactate, D-lactate, and LPS did not upregulate TLR5 gene expression in BREC. Primary BREC treated with flagellin (TLR5 ligand) had higher expression of interleukin-1ß (IL-1ß) (P < 0.05) than BREC treated with vehicle. In addition, BREC treated with IL-1ß had higher expression of antimicrobial peptides and C-X-C motif chemokine ligand 8 than BREC treated with vehicle (P < 0.05). These results suggest that ruminal TLR5 may recognize epithelial disruption via flagellin and mediate the immune response via IL-1ß during high-grain feeding or weaning.

Effect of feeding calf starter with calcium salts of medium-chain fatty acids on the growth and metabolic hormones in calves.

We investigated the effects of a calf starter supplemented with calcium salts of medium-chain fatty acids (MCFA-Ca) on growth and plasma hormone concentration in calves. Twelve Holstein calves were randomly assigned to two dietary groups (without supplementation [CON] and supplemented with MCFA-Ca [MCFA]) from 4 d of age. Calves were fed 1.0 kg/d of milk replacer until 5 wk of age and were completely weaned at 7 wk of age. Calves in the MCFA group received a calf starter containing 1% MCFA-Ca. dry matter intake (DMI) was measured daily, and body weight was measured weekly. Rumen fluid was collected at 13 wk of age to measure pH and volatile fatty acid concentration. Preprandial blood samples were collected weekly to measure the basal plasma hormone and metabolite concentrations. At 4, 8, and 13 wk of age, peri-prandial blood samples were collected every 30 min, from 60 min before feeding to 120 min after feeding, to observe metabolic responses to feeding. In addition, insulin sensitivity was assessed using euglycemic-hyperinsulinemic clamps at 4, 8, and 13 wk of age in three calves from each treatment. There were no differences in starter and hay DMI between the treatments. However, the average daily gain (ADG) after weaning was higher in the MCFA group than in the CON group. Weekly changes in plasma parameters did not differ between the treatments. Plasma concentrations of preprandial ghrelin and postprandial total ketone bodies at 13 wk of age were higher in the MCFA group than in the CON group. At 8 wk of age, peri-prandial plasma insulin concentrations were lower in the MCFA group than in the CON group. There were no differences between the treatments in terms of insulin sensitivity. The present study suggested that feeding weaning calves MCFA-Ca increases the ADG during the postweaning period, which may be mediated by endocrine signals, such as enhanced ghrelin secretion and decreased insulin secretion, without altering insulin sensitivity.

Calves are prone to growth retardation because of insufficient energy intake during the weaning transition period. Starch is the main energy source used in the formulation of calf starters. However, there is a concern that preweaned calves do not have sufficient functional rumen and small intestine to digest large amounts of starch, causing diarrhea, and decreased feed intake. Medium-chain fatty acids are easily accessible to calves and are expected to have functional properties, such as increasing the plasma concentration of ghrelin, which may enhance growth by stimulating growth hormone. The effect of calf starter supplementation with medium-chain fatty acids on growth performance and metabolism has not been evaluated previously and was evaluated in this study. Medium-chain fatty acids were fed in the form of calcium salts as pelleted solid feed. The results showed that feeding medium-chain fatty acids increased plasma ghrelin concentration, decreased insulin concentration, suggesting that these metabolic changes might be beneficial for calf growth performance.

Dietary 5-hydroxytryptophan improves sheep growth performance by enhancing ruminal functions, antioxidant capacity, and tryptophan metabolism: in vitro and in vivo studies.

Background: Hydroxytryptophan (5-HTP) can regulate the synthesis of 5-Hydroxytryptamine (5-HT) and melatonin (MT). In a previous metabolome analysis, we found that 5-HTP is an effective ingredient in yeast culture for regulating rumen fermentation. However, research on the effect of this microbial product (5-HTP) as a functional feed additive in sheep production is still not well explained. Therefore, this study examined the effects of 5-HTP on sheep rumen function and growth performance using in vitro and in vivo models. Methods: A two-factor in vitro experiment involving different 5-HTP doses and fermentation times was conducted. Then, in the in vivo experiment, 10 sheep were divided into a control group which was fed a basal diet, and a 5-HTP group supplemented with 8 mg/kg 5-HTP for 60 days. Results: The results showed that 5-HTP supplementation had a significant effect on in vitro DMD, pH, NH3-N, acetic acid, propionic acid, and TVFA concentrations. 5-HTP altered rumen bacteria composition and diversity indices including Chao1, Shannon, and Simpson. Moreover, the in vivo study on sheep confirmed that supplementing with 8 mg/kg of 5-HTP improved rumen fermentation efficiency and microbial composition. This led to enhanced sheep growth performance and increased involvement in the tryptophan metabolic pathway, suggesting potential benefits. Conclusion: Dietary 5-HTP (8 mg/kg DM) improves sheep growth performance by enhancing ruminal functions, antioxidant capacity, and tryptophan metabolism. This study can provide a foundation for the development of 5-HTP as a functional feed additive in ruminants' production.

Microencapsulation of lemongrass and mangosteen peel as phytogenic compounds to gas kinetics, fermentation, degradability, methane production, and microbial population using in vitro gas technique.

The purpose of the current study was to evaluate the impact of various doses of microencapsulated lemongrass and mangosteen peel (MELM) on gas dynamics, rumen fermentation, degradability, methane production, and microbial population in in vitro gas experiments. With five levels of microencapsulated-phytonutrient supplementation at 0, 1, 2, 3, and 4% of substrate, 0.5 g of roughage, and a concentrate ratio of 60:40, the trial was set up as a completely randomized design. Under investigation, the amount of final asymptotic gas volume was corresponding responded to completely digested substrate (b) increased cubically as a result of the addition of MELM (P < 0.01) and a cubic rise in cumulative gas output. The amount of MELM form did not change the pH and NH3-N concentration of the rumen after 12 and 24 h of incubation. However, methane production during 24 h of incubation, the levels were cubically decreased with further doses of MELM (P < 0.01) at 12 h of incubation. Increasing the dosage of MELM supplementation at 2% DM resulted in a significant increase in the digestibility of in vitro neutral detergent fiber (IVNDF) and in vitro true digestibility (IVTD) at various incubation times (P < 0.05), but decreased above 3% DM supplementations. Moreover, the concentration of propionic acid (C3) exhibited the variations across the different levels of MELM (P < 0.05), with the maximum concentration obtained at 2% DM. The populations of Fibrobacter succinogenes, Ruminococcus albus, Ruminococcus flavefaciens, and Megasphaera elsdenii revealed a significant increase (P < 0.05), while the quantity of Methanobacteriales decreased linearly with increasing doses of MELM. In conclusion, the inclusion of MELM at a concentration of 2% DM in the substrate which could enhance cumulative gas production, NDF and true digestibility, C3 production, and microbial population, while reducing methane concentration and Methanobacterial abundance.

Transcriptional response to an alternative diet on liver, muscle, and rumen of beef cattle.

Feed cost represents a major economic determinant within cattle production, amounting to an estimated 75% of the total variable costs. Consequently, comprehensive approaches such as optimizing feed utilization through alternative feed sources, alongside the selection of feed-efficient animals, are of great significance. Here, we investigate the effect of two diets, traditional corn-grain fed and alternative by-product based, on 14 phenotypes related to feed, methane emission and production efficiency and on multi-tissue transcriptomics data from liver, muscle, and rumen wall, derived from 52 Nellore bulls, 26 on each diet. To this end, diets were contrasted at the level of phenotype, gene expression, and gene-phenotype network connectivity. As regards the phenotypic level, at a P value < 0.05, significant differences were found in favour of the alternative diet for average daily weight gain at finishing, dry matter intake at finishing, methane emission, carcass yield and subcutaneous fat thickness at the rib-eye muscle area. In terms of the transcriptional level of the 14,776 genes expressed across the examined tissues, we found 487, 484, and 499 genes differentially expressed due to diet in liver, muscle, and rumen, respectively (P value < 0.01). To explore differentially connected phenotypes across both diet-based networks, we focused on the phenotypes with the largest change in average number of connections within diets and tissues, namely methane emission and carcass yield, highlighting, in particular, gene expression changes involving SREBF2, and revealing the largest differential connectivity in rumen and muscle, respectively. Similarly, from examination of differentially connected genes across diets, the top-ranked most differentially connected regulators within each tissue were MEOX1, PTTG1, and BASP1 in liver, muscle, and rumen, respectively. Changes in gene co-expression patterns suggest activation or suppression of specific biological processes and pathways in response to dietary interventions, consequently impacting the phenotype. The identification of genes that respond differently to diets and their associated phenotypic effects serves as a crucial stepping stone for further investigations, aiming to build upon our discoveries. Ultimately, such advancements hold the promise of improving animal welfare, productivity, and sustainability in livestock farming.

A meta-analysis of probiotic interventions to mitigate ruminal methane emissions in cattle: implications for sustainable livestock farming.

In recent years, the significant impact of ruminants on methane emissions has garnered international attention. While dietary strategies have been implemented to solve this issue, probiotics gained the attention of researchers due to their sustainability. However, it is challenging to ascertain their effectiveness as an extensive range of strains and doses have been reported in the literature. Hence, the objective of this experiment was to perform a meta-analysis of probiotic interventions aiming to reduce ruminal methane emissions from cattle. From 362 articles retrieved from scientific databases, 85 articles were assessed independently by two reviewers, and 20 articles representing 49 comparisons were found eligible for meta-analysis. In each study, data such as mean, SD, and sample sizes of both the control and probiotic intervention groups were extracted. The outcomes of interest were methane emission, methane yield, and methane intensity. For the meta-analysis, effect sizes were pooled using a fixed effect or a random effect model depending on the heterogeneity. Afterward, sensitivity analyses were conducted to confirm the robustness of the findings. Overall pooled standardized mean differences (SMDs) with their confidence intervals (CIs) did not detect significant differences in methane emission (SMD = -0.04; 95% CI = -0.18-0.11; P = 0.632), methane yield (SMD = -0.08; 95% CI = -0.24-0.07; P = 0.291), and methane intensity (SMD = -0.22; 95% CI = -0.50-0.07; P = 0.129) between cattle supplemented with probiotics and the control group. However, subgroup analyses revealed that multiple-strain bacterial probiotics (SMD = -0.36; 95% CI = -0.62 to -0.11; P = 0.005), specifically the combination of bacteria involved in reductive acetogenesis and propionate production (SMD = -0.71; 95% CI = -1.04 to -0.36; P = 0.001), emerged as better interventions. Likewise, crossbreeds (SMD = -0.48; 95% CI = -0.78 to -0.18; P = 0.001) exhibited a more favorable response to the treatments. Furthermore, meta-regression demonstrated that longer periods of supplementation led to significant reductions in methane emissions (P = 0.001), yield (P = 0.032), and intensity (P = 0.012) effect sizes. Overall, the results of the current study suggest that cattle responses to probiotic interventions are highly dependent on the probiotic category. Therefore, extended trials performed with probiotics containing multiple bacterial strains are showing the most promising results. Ideally, further trials focusing on the use of probiotics to reduce ruminal methane in cattle should be conducted to complete the available literature.

Biochar effect on sheep feed intake, growth rate and ruminant in vitro and in vivo methane production.

Biochar, which is the product of biomass pyrolysis, has been suggested as a feed supplement to improve performance in livestock systems and reduce greenhouse gas emissions. The aim of the current study was to investigate in vitro and in vivo potential of biochar to favourably modify rumen fermentation (e.g., an increase in total Short Chained Fatty Acid (SCFA) concentration and a change in SCFA profile), reduce methane emission and increase sheep growth performance. Four concentrates were produced with biochar inclusion of 0, 10, 23 and 46 g/kg DM. The experimental diets for the in vitro experiments consisted of straw and concentrate in a 60:40 ratio and included measurements of total gas and methane (CH4) production, pH, ammonia nitrogen, SCFA, and microbial assays (total bacteria and methanogenic archaea). Two in vivo experiments were performed where the animals received ad libitum forage with 0.4 kg concentrate daily. Experiment 1 investigated the daily DM intake of sheep while experiment 2 investigated daily growth rate and CH4 emission of lambs. The inclusion of biochar had no impact on in vitro total gas production (ml/200 mg DM substrate) (P = 0.81) and CH4 production (ml/200 mg DM substrate) (P = 0.93). In vitro total SCFA concentration increased (P < 0.05) while acetate to propionate ratio (A:P) tended to decrease (P = 0.05) with both doses of biochar. Total bacteria decreased with the highest biochar inclusion in vitro (P < 0.05). Sheep's DM intake (kg/d) increased when low and medium levels but not when a higher level of biochar was added to the diet (P < 0.001). The inclusion of biochar did not significantly impact the lamb's daily growth rate (g/d) (P = 0.61) or enteric CH4 emissions (g/kg DM) (P = 0.43). We conclude that biochar supplementation had no favourable impacts on in vitro and in vivo CH4 production or on lamb's growth rate. Further research with well-characterised biochar is needed to gain a better understanding of the potential of biochar as a feed additive for ruminant livestock.

Comparison of the Effects of Essential Oils from Cannabis sativa and Cannabis indica on Selected Bacteria, Rumen Fermentation, and Methane Production-In Vitro Study.

This study aimed to evaluate the effects of essential oils (EOs) extracted from Cannabis sativa L. and Cannabis indica Lam. on in vitro ruminal fermentation characteristics, selected rumen microbial populations, and methane production. GC-MS analyses allowed us to identify 89 compounds in both EOs. It was found that E-ß-caryophyllene predominated in C. sativa (18.4%) and C. indica (24.1%). An in vitro (Ankom) test was performed to analyse the control and monensin groups, as well as the 50 µL or 100 µL EOs. The samples for volatile fatty acids (VFAs), lactate, and microbiological analysis were taken before incubation and after 6 and 24 h. The application of EOs of C. indica resulted in an increase in the total VFAs of acetate and propionate after 6 h of incubation. The applied EOs had a greater impact on the reduction in methane production after 6 h, but no apparent effect was noted after 24 h. Lower concentrations of C. sativa and C. indica had a more pronounced effect on Lactobacillus spp. and Buryrivibrio spp. than monensin. The presented findings suggest that C. sativa and C. indica supplementation can modify ruminal fermentation, the concentrations of specific volatile fatty acids, and methane production.

Separate offering of forages and concentrates to lactating dairy cows: Effects on lactational performance, enteric methane emission, and efficiency of nutrient utilization.

The objective was to evaluate the effects of separate offering of feed ingredients (SF) and frequency of concentrate feeding versus offering a TMR, on lactational performance, ruminal fermentation, enteric CH4 emissions, nutrient digestibility, N use efficiency, milk fatty acid profile, and blood variables in mid-lactation dairy cows. Twenty-four Holstein cows (12 primi- and 12 multiparous) averaging (±SD) 141 ± 35 DIM and 43 ± 6 kg/d of milk yield (MY) at the beginning of the study were used in a replicated 3 × 3 Latin square design experiment with 3 periods of 28 d each, composed of 7 d for adaptation to the diets, 11 d for estimation of net energy and metabolizable protein requirements, and 10 d for data and samples collection. Cows were grouped based on parity, DIM, and MY into 4 Latin squares. Treatment allocation was balanced for carryover effects, and cows within square were assigned to (1) basal diet fed ad libitum as TMR; (2) basal diet fed as SF with forages fed ad libitum and concentrates fed 3×/d (SF×3); or (3) basal diet fed as SF with forages fed ad libitum and concentrates fed 6×/d (SF×6). Compared with TMR, SF decreased total DMI by 1.2 kg/d. Treatments did not affect MY, milk components, or ECM yield, except for a decrease in milk fat concentration and an increase in milk urea N by SF×3, compared with TMR. Feed efficiency (kg of MY/kg of DMI) was increased by 7% in SF, compared with TMR. Ruminal molar proportion of acetate and acetate-to-propionate ratio were decreased, whereas molar proportion of propionate was increased by SF×3, compared with TMR and SF×6. There was a 9% decrease in daily CH4 production by SF, compared with TMR. Enteric CH4 yield (per kg of DMI) was not affected by treatments in the current study. Methane intensity per kilogram of MY tended to be decreased by 10% in SF, compared with TMR. The sums of odd- and branched-chain, odd-chain, and anteiso milk fatty acids tended to be or were increased by SF, compared with TMR. Intake of nutrients tended to be or were decreased by SF, compared with TMR. The digestibility of amylase-treated NDF tended to be decreased and ADF digestibility was decreased by 3% in SF, compared with TMR. Urinary and fecal N excretions were not affected by treatments. As a percentage of total N intake, separate offering of feed ingredients increased milk N secretion, indicating an increased N use efficiency by SF, compared with TMR. Blood total fatty acid concentration was decreased by SF relative to TMR. Compared with both TMR and SF×6, SF×3 increased blood urea N concentration. Overall, feed and N use efficiencies were increased by separate offering of feed ingredients, and increasing the frequency of concentrate feeding promoted ruminal fermentation effects similar to those obtained by feeding a TMR.

Exploring the Interplay between the Hologenome and Complex Traits in Bovine and Porcine Animals Using Genome-Wide Association Analysis.

Genome-wide association studies (GWAS) significantly enhance our ability to identify trait-associated genomic variants by considering the host genome. Moreover, the hologenome refers to the host organism's collective genetic material and its associated microbiome. In this study, we utilized the hologenome framework, called Hologenome-wide association studies (HWAS), to dissect the architecture of complex traits, including milk yield, methane emissions, rumen physiology in cattle, and gut microbial composition in pigs. We employed four statistical models: (1) GWAS, (2) Microbial GWAS (M-GWAS), (3) HWAS-CG (hologenome interaction estimated using COvariance between Random Effects Genome-based restricted maximum likelihood (CORE-GREML)), and (4) HWAS-H (hologenome interaction estimated using the Hadamard product method). We applied Bonferroni correction to interpret the significant associations in the complex traits. The GWAS and M-GWAS detected one and sixteen significant SNPs for milk yield traits, respectively, whereas the HWAS-CG and HWAS-H each identified eight SNPs. Moreover, HWAS-CG revealed four, and the remaining models identified three SNPs each for methane emissions traits. The GWAS and HWAS-CG detected one and three SNPs for rumen physiology traits, respectively. For the pigs' gut microbial composition traits, the GWAS, M-GWAS, HWAS-CG, and HWAS-H identified 14, 16, 13, and 12 SNPs, respectively. We further explored these associations through SNP annotation and by analyzing biological processes and functional pathways. Additionally, we integrated our GWA results with expression quantitative trait locus (eQTL) data using transcriptome-wide association studies (TWAS) and summary-based Mendelian randomization (SMR) methods for a more comprehensive understanding of SNP-trait associations. Our study revealed hologenomic variability in agriculturally important traits, enhancing our understanding of host-microbiome interactions.

Agro-industrial by-products as ruminant feed: Nutritive value and in vitro rumen fermentation evaluation.

In recent years, agricultural by-products have generated increasing interest as ruminant feed. In a completely randomized design with five experimental treatments, this in vitro study investigated the nutritional value of citrus pulp and onion peel as alternative feed for ruminants and their effects on rumen fermentation, digestibility, and gas production. The first group was the control (50% grass hay/50% concentrate mixture). The other four treatments represented citrus pulp and onion peel at inclusion levels of 10 and 20%, replacing the expensive, high-quality feed ingredients such as the concentrate mixture. The chemical composition showed that citrus pulp is an energy-rich material that could be included up to 20% to replace part of the concentrate in a mixed diet without any adverse impacts on rumen fermentation parameters. The onion peels were rich in fiber and minerals. Their inclusion in the diet of over 10% had detrimental effects on rumen fermentation. The inclusion of either citrus pulp or onion peel in the diet did not have the potential to reduce enteric methane production. In conclusion, citrus pulp showed promising results as a new feed for ruminants. It was effective when included in up to 20% of a ruminant diet, replacing the concentrate mixture.

Effects of the Interaction between Rumen Microbiota Density-VFAs-Hepatic Gluconeogenesis on the Adaptability of Tibetan Sheep to Plateau.

During the adaptive evolution of animals, the host and its gut microbiota co-adapt to different elevations. Currently, there are few reports on the rumen microbiota-hepato-intestinal axis of Tibetan sheep at different altitudes. Therefore, the purpose of this study was to explore the regulatory effect of rumen microorganism-volatile fatty acids (VFAs)-VFAs transporter gene interactions on the key enzymes and genes related to gluconeogenesis in Tibetan sheep. The rumen fermentation parameters, rumen microbial densities, liver gluconeogenesis activity and related genes were determined and analyzed using gas chromatography, RT-qPCR and other research methods. Correlation analysis revealed a reciprocal relationship among rumen microflora-VFAs-hepatic gluconeogenesis in Tibetan sheep at different altitudes. Among the microbiota, Ruminococcus flavefaciens (R. flavefaciens), Ruminococcus albus (R. albus), Fibrobactersuccinogenes and Ruminobacter amylophilus (R. amylophilus) were significantly correlated with propionic acid (p < 0.05), while propionic acid was significantly correlated with the transport genes monocarboxylate transporter 4 (MCT4) and anion exchanger 2 (AE2) (p < 0.05). Propionic acid was significantly correlated with key enzymes such as pyruvate carboxylase, phosphoenolpyruvic acid carboxylase and glucose (Glu) in the gluconeogenesis pathway (p < 0.05). Additionally, the expressions of these genes were significantly correlated with those of the related genes, namely, forkhead box protein O1 (FOXO1) and mitochondrial phosphoenolpyruvate carboxykinase 2 (PCK2) (p < 0.05). The results showed that rumen microbiota densities differed at different altitudes, and the metabolically produced VFA contents differed, which led to adaptive changes in the key enzyme activities of gluconeogenesis and the expressions of related genes.

Lactational performance, ruminal fermentation, and enteric gas emission of dairy cows fed an amylase-enabled corn silage in diets with different starch concentrations.

This study investigated the effects of feeding an amylase-enabled corn silage (ACS) on the performance and enteric gas emissions in lactating dairy cows. Following a 2-wk covariate period, 48 mid-lactation Holstein cows were assigned to 1 of 3 treatments in a 10-wk randomized complete block design experiment. Treatments were diets containing the same proportion of corn silage (40% of dietary DM) as follows: (1) a conventional hybrid corn silage control (CON), (2) ACS replacing the control silage (ADR), and (3) the ADR diet replacing soybean hulls with ground corn grain to achieve the same dietary starch concentration as CON (ASR). Control corn silage and ACS were harvested on the same day and contained 40.3% and 37.1% DM and (% of DM): 37.2% and 41.0% NDF and 37.1% and 30.0% starch, respectively. Enteric gas emissions were measured using the GreenFeed system. Two cows were culled due to health-related issues during the covariate period. Ruminal fluid was collected from 24 cows (8 per treatment) using the orogastric ruminal sampling technique. When compared with CON, cows fed ADR had increased DMI during experimental wk 3, 4, and 9, but treatment did not affect milk or ECM milk yields (39.0 kg/d on average; SEM = 0.89). Compared with CON, feed efficiency (per unit of milk, but not ECM) tended to be lower for ADR, whereas milk true protein concentration (a tendency) and yield were lower for ASR. Milk urea N was decreased by both ADR and ASR diets relative to CON. Compared with CON, daily CH4 emission and emission intensity were increased by ADR but not ASR. Total protozoal count tended to be increased by both diets formulated with ACS when compared with control corn silage. Total-tract digestibility of dietary NDF was greater for ASR, and that of ADF was greater for both ADR and ASR versus CON. The molar proportion of acetate (a tendency) and acetate-to-propionate ratio were increased by ADR, but not ASR, when compared with CON. Replacement of CON with ACS (having lower starch concentration) in the diet of dairy cows increased DMI during the initial weeks of the experiment, maintained ECM, tended to decrease feed efficiency, and increased enteric CH4 emissions, likely due to increased intake of digestible fiber, compared with CON.

Environmental impact of phytobiotic additives on greenhouse gas emission reduction, rumen fermentation manipulation, and performance in ruminants: an updated review.

Ruminal fermentation is a natural process involving beneficial microorganisms that contribute to the production of valuable products and efficient nutrient conversion. However, it also leads to the emission of greenhouse gases, which have detrimental effects on the environment and animal productivity. Phytobiotic additives have emerged as a potential solution to these challenges, offering benefits in terms of rumen fermentation modulation, pollution reduction, and improved animal health and performance. This updated review aims to provide a comprehensive understanding of the specific benefits of phytobiotic additives in ruminant nutrition by summarizing existing studies. Phytobiotic additives, rich in secondary metabolites such as tannins, saponins, alkaloids, and essential oils, have demonstrated biological properties that positively influence rumen fermentation and enhance animal health and productivity. These additives contribute to environmental protection by effectively reducing nitrogen excretion and methane emissions from ruminants. Furthermore, they inhibit microbial respiration and nitrification in soil, thereby minimizing nitrous oxide emissions. In addition to their environmental impact, phytobiotic additives improve rumen manipulation, leading to increased ruminant productivity and improved quality of animal products. Their multifaceted properties, including anthelmintic, antioxidant, antimicrobial, and immunomodulatory effects, further contribute to the health and well-being of both animals and humans. The potential synergistic effects of combining phytobiotic additives with probiotics are also explored, highlighting the need for further research in this area. In conclusion, phytobiotic additives show great promise as sustainable and effective solutions for improving ruminant nutrition and addressing environmental challenges.

Lyophilized rumen fluid as a ruminal fermentation modifier in high grain-fed acidotic goats.

Rumen cud transfaunation re-establishes rumen micro environment and improves fermentation in recipient animals affected with digestive disorders. Preserving rumen cud or fluid will increase its availability for the treatment of rumen fermentation disorders, without having to maintain donor animals. Rumen fluid collected from healthy goats, fed standard ration having roughage 70% and concentrate 30%, was lyophilized (prefreezing -80 °C, 48 h; lyophilization -45 °C, 32 h) using 5% glycerol as cryoprotectant. The 16 S metagenome analysis of the lyophilized rumen fluid (LRF) revealed an abundance of Prevotella (33.2%). Selenomonas ruminantium (1.87%) and Megasphaera elsdenii (0.23%) were also present. Twenty-four goats having history of high grain feeding and exhibiting clinical symptoms of rumen fermentation disorders were randomly distributed into either one of the two treatment groups viz., T1 = oral administration of LRF 31 g/animal/day and T2 = oral administration of sodium bicarbonate (SB) 15 g/animal/day. Post intervention LRF and SB, improved animal body condition, feed intake, fecal consistency, elevated the ruminal pH at 48 h, reduced propionate and lactate at 48 h, reduced total volatile fatty acids (TVFA) and ammonia nitrogen at 24 h. Significant reduction in serum blood urea nitrogen (BUN) and urea levels were observed even from 24 h post intervention irrespective of the treatments. LRF significantly improved acetate and decreased propionate production compared to SB. LRF at 7.5% (v/v) can thus be used to counteract ruminal fermentation disorders in goats sequel to high grain ration.

Effect of nonstructural carbohydrates on production performance, rumen metabolism and rumen health in lambs fed with isocaloric and isonitrogenous complete diets.

Nonstructural carbohydrates (NSC) are readily fermentable in the rumen and, are a critical factor while preparing protracted feed for higher animal performance. Four isocaloric and isonitrogenous complete feeds were prepared for this investigation to contain varying levels of nonstructural carbohydrates viz., 40.13 (NSC1), 45.21 (NSC2), 50.00 (NSC3) and 55.85 (NSC4) per cent, respectively. The four isocaloric and isonitrogenous complete feeds were tested in 32 Mecheri ram lambs (around three months of age) in a completely randomised block design (n = 8), and the lambs were fed their respective feed for six months. The study revealed that the increased NSC level in the complete diet increased the body weight and weight gain linearly (P < 0.05). The dietary NSC level affected the dry matter consumption in a quadratic manner (P < 0.05) and the lambs of the NSC4 group consumed significantly (P < 0.05) less DM compared to other dietary groups. The overall average feed conversion efficiency differed significantly (P < 0.05) among dietary groups. The correlation between dietary NSC level and faecal score was quadratic (r2 = 62.7, P < 0.05). The rumen pH, total nitrogen and NH3-N concentration were linearly decreased (P < 0.05) and the molar proportion of total short-chain fatty acids and propionic acid were increased (P < 0.05). The energy loss expressed as methane production was significantly (P < 0.01) lower for the high NSC diet-fed lambs. The lambs fed on a low NSC diet had significantly (P < 0.05) lower carcass weights, dressing percentage and loin eye area. The per cent share of rumen weight in the total fore stomach and the rumen papillae measurements length, width and surface area were significantly (P < 0.05) higher in high NSC diet-fed lambs. Increased levels of NSC in the diet increased (P < 0.05) fat deposition in the internal organs. The saturated fatty acids content in the meat was significantly (P < 0.05) lowered, whereas, the oleic acid and linoleic acid were increased (P < 0.05) as the NSC level increased in the diet. The study revealed that as the level of NSC increased in the complete diet there was a concomitant improvement in the final body weight, ADG and feed efficiency of post-weaned Mecheri lambs. It can therefore be recommended that the complete feed with 50 per cent NSC levels would be optimum to reap maximum returns from fattening Mecheri lambs.